Tick bite by Haemaphysalis megaspinosa – First case

ARTICLE

Although local tick bite reactions such as tick bite granuloma, autoeczematization [1], temporary alopecia [2], ecchymosis, blisters and pruritus [3] have been described, patients are usually unaware of the bite and notice only a papule or nodule at the bite site. Ticks are important vectors of diseases such as a number of viral [4] and rickettsial infections [5], and Lyme disease [6]. Five genera and 17 species were reported from Japan [7] as the ticks that bite human skin, namely Ixodes (I.) ovatus, I. persulcatus, I. nipponensis, I. acutitarsus, I. monospinosus, I. asanumai, I. turdus, Haemaphysalis (H.) longicornis, H. flava, H. campanulata, H. japonica, H. hystricis, Amblyomma (Am.) testudinarium, Am. americanum, Rhipicephalus sanguineus, Argas (A.) vespertilionis, and A. japonicus. On the other hand, I. dammini, I. pacificus, I. scapularis, Am. americanum, Dermacentor (D.) andersoni and D. variabilis have been reported in USA [8]. Tick bite by H. megaspinosa [9, 10], which may be one of the vectors of Japanese spotted fever [5, 11] has not been reported so far.

Case report

A 5-year-old girl with a gray nodule on the skin at the right occipital area consulted Ogaki Municipal Hospital on November 9, 1999. She had gone on a picnic twice to Mt. Ibuki (1377 m above the sea level) in the Shiga district in the central part of Japan on November 3 and 7, 1999. She noticed the tick on November 8 (Fig. 1). The size of the nodule was approximately 6 x 4 x 3 mm. This tick was alive and struggled with four pairs of legs when we touched it with our fingers. The tick was surgically removed on the same day. She complained of nausea, vomiting and diarrhea with fever of 39-40° C from November 12, but skin eruption was not observed. These symptoms continued until November 15. Laboratory data were all within normal limits except for elevation of CRP. Weil-Felix reactions, including reactions to OXK, OX19, and OX2, were all negative. Both the IgG and IgM antibodies to Borrelia burgdorferi were negative.

The tick was identified as an adult female of H. megaspinosa from its morphological characteristics [9, 10]. The tick possessed a capitulum, an unsegmented body and four pairs of legs (Fig. 2). The scutum was subround (1.18 mm long by 1.17 mm wide at maximum) and covered only a small anterior part of the dorsum as usually observed in the female, with eyes absent (Fig. 3). The posterior site of the idiosoma showed a festoon which is characteristic of Haemaphysalis species. The hypostome was short, and the palpi were also short and cone-shaped. The coxae of the first legs had internal spurs but no external spurs. The coxae of the second and third legs were small and had spurs at the center of the posterior edge. The coxae of the fourth legs had wide and large internal spurs characteristic of H. megaspinosa (Fig. 4). The spiracular plates were subcircular.

Discussion

The tick in the present case was identified morphologically. H. megaspinosa is close to H. flava in general appearance but the body color is more brownish and darker, and the body size is markedly larger in both sexes compared to H. flava [9, 10]. In the female of this species, coxa IV has a longer spur than H. flava [9, 10] (Fig. 4). Adults of H. megaspinosa have been collected from a wild boar, deer and Japanese serow in the Miyazaki, Mie, and Shiga districts [10] where the tick bit the skin of the present patient in Japan.

Haemaphysalis species is well known to be an important vector of Rocky Mountain spotted fever, Siberian tick typhus and Colorado tick fever [12]. Furthermore, the causative agent of Japanese spotted fever, Rickettsia (R.) japonica, is transmitted by ticks, especially by the Haemaphysalis species [5]. Hemolymph test by immunoperoxidase stain using R. japonica-specific monoclonal antibody showed positive in H. flava, H. formosensis, H. hystricis, and H. longicornis [5]. Gene of R. japonica was recently detected by polymerase chain reaction in H. flava [13] and H. megaspinosa [11].

Infected patients with Japanese spotted fever have high fever, headache and characteristic erythema which develops on the extremities and spreads to all parts of the body including palms and soles. Eschar is usually observed in this disease, though less than that in Tsutsugamushi disease. More than a hundred cases of Japanese spotted fever have been reported in the southwestern and central areas of Japan since it was first described in 1984. Weil-Felix tests usually show positive OX2 serum agglutinins but negative OXK and OX19. Since Weil-Felix tests were negative, and neither eschar nor characteristic erythema was observed, the diagnosis of Japanese spotted fever was not made in the present case, despite fever probably 5 or 9 days after the tick bite. However, infection by an undefined causative agent such as unknown rickettsia could not be excluded.

CONCLUSION

Acknowledgements

We are very grateful to Dr. H. Fujita, Ohara General Hospital, for his valuable suggestions.

Article accepted on 27/3/00

REFERENCES

1. Shasky DR. Tick bite granuloma with autoeczematization. Arch Dermatol 1972; 106: 916.

2. Heyl T. Tick bite alopecia. Clin Exp Dermatol 1982; 7: 537-42.

3. Hoogstraal H, Gallagher MD. Blisters, pruritus and fever after bites by the Arabian tick Ornithodorus (Alectorobius) muesebecki. Lancet 1982; 2: 288-9.

4. Takashima I. Epidemiology of tick-borne encephalitis in Japan. Com Immunol Microbiol Infect Dis 1998; 21: 81-90.

5. Mahara F. Japanese spotted fever: report of 31 cases and review of the literature. Emerg Infect Dis 1997; 3: 105-11.

6. Miyamoto K, Nakao M, Sato N, Mori M. Isolation of Lyme disease spirochetes from an ixodid tick in Hokkaido, Japan. Acta Tropica 1991; 49: 65-8.

7. Woo IC, Baba S, Suzuki H, Kawabata M. A case of tick bite with Ixodes turdus Nakatsuji. J Dermatol 1990; 17: 56-8.

8. Wilson DC, King LE Jr, Ticks. In: Freedberg IM, Eisen AZ, Wolff K, Austen KF, Goldsmith LA, Katz SI, Fitzpatrick TB, eds. Dermatology in general medicine. 5th edition, New York: McGraw-Hill; 1999: 2687-8.

9. Saito Y. Studies on ixodid ticks, X. Haemaphysalis megaspinosa n. sp. (Ixodoidea, Ixodidae) from Kanagawa Prefecture, Japan. Acta Med Biol 1969; 17: 87-96.

10. Yamaguti N, Tipton VJ, Keegan HL, Toshioka S. Ticks of Japan, Korea, and the Ryukyu Islands. Brigham Young Univ Sci Bull Biol Ser 1971; 15: 100-5.

11. Katayama K, Inada T, Furuya Y, Yoshida Y, Imai M. The detection of the spotted fever group rickettsiae gene from ticks in Kanagawa prefecture. Abstract of 6th Conference of Rickettsia, 1999: 10.

12. Burns DA. Ticks (acarina, parasitiformes, metastigmata). In: Champion RH, Burton JL, Burns DA, Breathnach SM, eds. Textbook of dermatology. 6th edition, New York; Blackwell Science; 1998: 1454-6.

13. Katayama K, Furuya Y, Yoshida Y, Kaiho I. Spotted fever group rickettsiosis and vectors in Kanagawa Prefecture. J Jpn Assoc Infect Dis 1996; 70: 561-8.